Good Morning Dan, 

Thank you for contacting the U of M Extension Service. 

As with any herbicide read the label in detail. 

I am not familiar with each different herbicide. The first thing I do is download the label for the herbicide and read the label in detail. 

Here are some highlights of the label: 

I am unable to copy text out of the pdf. 

On page 5 there is a surface water advisory indicating a potential for runoff from the soil for several weeks after application. 

On page 7 it discusses including a surfactant and a second application may be necessary. Also, this may turn your turf grass foliage white in some cases. 

On page 7 there is a "Use precautions and restrictions" that indicates you should not plant any crop other than turfgrass for 18 months (residual effects) and do not use the grass clippings for any kind of mulch under trees or on gardens. 

On page 10: There is also a list of plants the herbicide will kill. Some of these are good pollinator plants. 

Here is a link from the DNR about garter snakes: https://www.dnr.state.mn.us/reptiles_amphibians/commongartersnake.html

After reading the label in detail, if you decide to apply the herbicide it is your choice.  

I am also a Pollinator Ambassador for the U of M Bee Lab. 

With an 18 month residual affect on your soil, I personally would not use the product. You could mow and bag the dandelion heads. I do not spray or apply herbicides to my yard. In a few weeks the dandelions will subside. Applying the product in the evening should not make a difference on the residual affects. They will exist. 

Your garter snakes food sources may be affected by the herbicide. If they don't die from the herbicide, they will leave your yard. 

You might consider planting a bee lawn insteadhttps://extension.umn.edu/landscape-design/planting-and-maintaining-bee-lawn

Your county Soil and Water Conservation District may have grant funding and also guidance on planting a bee lawn. Also the Lawns to Legumes program:  https://bwsr.state.mn.us/l2l  Will  provide some funding and expert guidance on how to do it. 

Good Luck!